Yielding torque indicating tool



June 20, 1950 A. J. MELLERT YIELDING ToRQUE INDICATNG ToorJ Filed Nov. 30, 1945 Nm. xm. XM.

TL YQ mw N j il INVENTOR. ALLEN J. MELLERT @M2M-Www Patented June 20, 1950- Allen J. Mellert, Cleveland, Ohio, assignor, by mesne-assignments, to Diversified Designing &

Machine lProducts riorporation,

Cleveland,

Ohio,ia corporation .of Ohio Application November 30, 1945,Serial No.'63l,9'v72 8 Claims.

' This invention relates totools andiparticularly to those having' a work-'engaging head and a handle by means of whichforce or torque is applied to the work. Among the tools lto which the invention is applicable may be mentioned Wrenches, screw drivers, .and various forms of tamping or punching devices.

In hand tools of thesetypes'itghas beengfound desirable to indicate in someway to the operator when a predetermined amount of torque'o-r force has been applied tothe Work. Such an indication is Fnecessary Where an excessive "amount of tightening of a ,fastening means would injure .either the article ibeing'fastened lor the `fastening means itself, and in other cases 'is kdesirable in saving a needless amount of work exceeding that of thepredetermined amount found to be suincient for a particular application.

In devices of this type, some 'formjof resilient means, usually in 'the form of a coil spring, is 1 `used to drive the work-engaging member, and ,it is usually lnecessary to multiply theforce .exerted'by the spring s o that the lspring itself need not be vexcessively stiff and diicultj to control. vIn

the past various -forms of Vmechanical Vlinkages have been devised to accomplish `this multiplication of Ythe force. Friction between the moving parts, however, has been a constant source of annoyance in vitiating'the results, asvany change in the ease `with which the parts articulate is reflected in the amount -of torque or Aforce applied to'the work member.

An object of the present invention is to provide a device which will accomplish the multiplication of force between the resilient 'driving f 'means and the work-engagingfmember in a tool and which `will not be subject to the above objections- Another obj ect is to provide raneadjustment` for the 4force 'applying means whereby to predeter- 4mine theforce or 'torque -at which the tool ropcrates.

Another Objectis to prov-ide a visual indicating means to apprise the operator that vthe '.predeterminedeffect has been accomplished.

A lfurther "object is 'to vprovide means whereby the resistanceoeredby'thefhandle tofthe efforts of the operator is :suddenly `relaxed 4when the predetermined --eiect has "been produced, ithus furnishing him an vindication 2in addition tothe visual one.

These :objects I accomplish in iai-simple and effective manner Vfoy-providing a work-engaging member 'which moves :relative .to the handle when,` While lthe 'memberiis stopped by fthe reylli 2 sistance of the work, the handle'continues-on, and -by providing `'a differential cylinder wherein the 'unit pressure produced -by a small piston, under action of amain spring, is multiplied-over theareaofalarge piston to provide a large force for Vapplication to 'the lwork-engaging lmember and wherein the working fluid, such as oil, maintains the pistons 'in lubricated condition. The operator is advised when the predetermined effect has been produced 'by the sudden relaxation of 'thedrive furnished bythe above means, and in addition an electric vlight is provided which cooperates with the V4other parts to give him the same information.

YReferring now to the drawings, Fig. l is an axial section through -a wrench embodying my invention; Fig. 2 isf'an elevational view thereof; Fig. 3 Iis a view similar to Fig. l but showing the parts in different `relative positions; land Fig. A4 is a transverse 4section taken on the `line Liin-"i of Fig.-3.

In the 4vdrawings' have illustrated alpreerred embodimentvof myfinvention iii-which a ihandle 1:0 is provided with a jaw iii fpivotedfat l! to extensions orrears I3 `on Athe handle. The jaw itself may beseparable yfroma lpivoted block `so as @to ibe interchangeable 4with jaws of iother -sizes or with other types of work-engaging heads. Normally, ythe ja-w or head is -orcibly held .in alignment with'the vhandle in the l'position illustrated in Fig. "3. V*In operation, however, when a workpiece, such as fthe nut `N, has been 'tightened to such adegreethat la torduezabove a predetermined .amount must be applied to turn it furtlier, the alignment maintaining force is overcome. Since the rotation of the head is then retarded, "continued movement of the )handle-by .the :operator .causes'the'tool .to break .at the pivot l2. `The sudden `relamitiOn.indicates to the operator that the desired torque has been vAdditional indication is r'furn-ished yby a visual signal in the formof :anfelectriclightfthecircuit of which is closedupon a Apredeterminedamount of yrelative turning fof ithe 'handle `and jaw.

"The lalignment maintaining :force `met?iunior-21:'. is preferably produced-by `means of xcoinpres.- sion spring l5 :bearing atbneend'againsta -reaction member v I `l :and at tthe. other end against a spring seat I1 on an elongated .piston yor ram 18. The ram I8 fisslida'ble infa differential hyn draulic cylinder |19 which is provided with an. appropriate packing vor vseal -at 412|). Thecylinder is enlarged vat' 2| to accommodatea piston of .an iareafmany .times fthatzof ,a V`piston i8. The piston 12 .ais `provided with a cupeshaped washer 23 of leather or other suitable material and a light spring 24 is interposed between the washer and the end of the large cylinder to maintain the parts in proper position. The piston 22 is also provided With a hardened renewable wearing surface at 25 which is adapted to bear against the pivoted block I4. A flat 26 is formed on the block, for engagement with the piston, and terminates in slightly rounded corners 2l. Normally, the piston 22 bears against the flat to hold the block and jaw in alignment with the handle. Upon relative turning of the block, however, a corner 2l operates as a high point, or portion of increased radius, on a cam and cams the piston inwardly. Abutments may be provided at 44 to prevent inadvertent ejection of the piston before the block I4 is secured in place.

It Will be understood that the cylinder 2I is filled with oil or other suitable uid and that the force exerted by the spring I5 through the ram I8 is multiplied, by the ratio of the squares of the diameters of the two pistons, to provide a greatly increased force against the block. Conversely, a small movement imparted to the piston 22 by means of the pivoting block produces a correspondingly greater movement of the piston I8, and hence a longer spring can be utilized at I5, the advantage of which will be later pointed out.

To accommodate the electric light bulb and its battery, a housing 30 is provided, which housing forms an extension of the handle. A socket 3l for the bulb 32 is clamped against the end of the housing by means of a threaded, transparent cover 33. The battery 34 is pressed into contact with the bulb by a spring 35 which, in turn, makes contact with the end of the battery and with an insulated, elongated contact 36 carried in an inwardly extending sleeve 31 on the housing. The housing is rotatably adjustable with respect to the handle IIJ and may be clamped in adjusted position, through the intermediacy of a clamping nut 38 which engages a rib 39 on the housing and is threaded on the handle.

A circuit for the light is established when the piston I8 has been ejected suiciently far from the hydraulic cylinder to engage the contact 3B. Current may then ow from the battery 34 through the light 32, socket 3 I, housing 30, sleeve 3l, reaction member I6, spring I5, spring seat I'I, piston I8, contact 36, and spring 35, and back to the battery. This circuit is normally open at the Contact 36, as illustrated in Fig. 3.

The compression spring I5 may be adjustably pre-loaded so as to predetermine the torque at which the tool will operate. To this end the reaction member I 6 is provided in the form of a traveling nut, threaded upon the sleeve 3'! of the housing 3U. Lugs 40 are integrally formed on the member and are slidable in slots 4I in the handle I0, to prevent rotation of the traveling nut. One or both of the lugs may conveniently serve as an indicator, as shown at 42, for cooperation with suitable indicia on the handle, whereby the tool may be calibrated in inchounces, foot-pounds, or other suitable units. The position of the reaction member, and thereby the pre-loading of the spring, may be accomplished by loosening the clamping nut 39 and rotating the housing 30.

The provision of the force multiplying hydraulic feature enables the use of a lighter and longer spring and a number of advantages are gained thereby. One advantage is that the parts need not be as rugged, and therefore as wasteful of material, as would be necessary with a far more powerful spring. Another advantage is that the increased length of the spring enables an increase in the length of adjustment required to cover the intended range of the tool. This results in a greater spread of the indicia marks with an attendant increase in accuracy of adjustment. An additional advantage derived from the greater length of travel is the increase in accuracy with which the position of the electrical contact for the visual indicator may be controlled.

Y While I have illustrated the tool as having a pivoted head which is normally maintained in position by the force of the piston against a flat cam formation, the cam being adapted to move the piston when the head swings from normal position, it will be apparent that other arrangements could be used.

Thus while I have illustrated a specic embodiment of my invention, I do not intend to be limited thereby, as the changes and modifications here suggested and others apparent to one skilled in the art may be made within the spirit and scope of my invention.

I claim:

1. A tool comprising a hollow handle, a workengaging head pivotally carried by the handle and normally aligned therewith, a cam drivingly secured to the head, a hydraulic cylinder in the handle, the cylinder having an incompressible iluid therein, two pistons of different areas slidable in the cylinder, the larger piston being operable by the cam, an adjustable reaction member, a compression spring between the smaller piston and the reaction member, a battery, an electric light, a stationary contact, and a circuit in part through the contact and through the smaller piston and completed when, upon suicient misalignment of the head, the smaller piston is forced a predetermined distance from the cylinder to compress the spring and engage the contact.

2. A yielding torque applying tool comprising a hollow handle, a pair of communicating aligned cylinders within the handle one materially larger than the other, the cylinders having in incompressible iluid therein, a work-engaging head pivotally carried by the handle, a piston positioned in each of the, cylinders with the larger cylinder receiving a larger piston than the other cylinder, means lto slide the larger piston axially into the cylinder upon relative pivoting movement of the head with respect to the handle, a spring resisting the outward movement of the smaller piston from its cylinder, the head being independent of the cylinders and both of the pistons in the work engaging action of the head and not being connected to the cylinders and pistons, and an adjustable spring-acting device within the handle opposing resistance to the outward movement of the smaller piston.

3. In a yielding torque applying tool, the combination of a hollow handle having adjacent one end a comparatively large cylinder and having within the handle back of such large cylinder a smaller cylinder in communication with the large cylinder, the cylinders having an incompressible iluid therein, a piston in the large cylinder, av Work-engaging head pivotally carried by the handle and coacting with an abutment member at the outer end of the piston in the large cylinder, a piston rod .axially slidable from the opposite end into the small cylinder, a spring seat secured to said piston rod beyond its cylinder, a compression spring within the handle bearing at one end against the spring seat, an adjustable abutmentv member within the handle against which the other end of the spring bears and a rotatable device on the handle for variably posi- 'tioning the abutment member to compress the spring adjustably.

4. A tool of the character described comprising a tubular handle carrying within it adjacent one end a comparatively large cylinder and then a smaller cylinder communicating with the large cylinder, the cylinders having an incompressible iluid therein, a work engaging member pivoted to the handle and having `a cam action against a piston in the large cylinder, a piston rod occupying the smaller cylinder and extending in the opposite direction, a spring seat carried by the piston rod, a longitudinally adjustable abutment within the handle having a lug occupying a longitudinal slot in the handle and a helical spring within the handle compressed between said abutment member and spring seat, whereby the amount of compression of the spring may be visibly indicated by graduations on the handle adjacent the slot.

5. A yielding torque applying tool comprising a hollow handle forming a cylinder and carrying adjacent one end a pivotally mounted workengaging head, a piston slidably mounted in the handle and carrying a removable abutment screw against which the pivoted head may exert a camming action, a smaller cylinder within the handle in communication with the larger cylinder, the cylinders having an incompressible fluid therein, a piston in the smaller cylinder projecting beyond it and carrying a spring seat, a springengaging said seat and means for putting said spring under compression.

6. A tool comprising a hollow handle, a workengaging head pivotally carried by the handle and normally aligned therewith, a cam drivingly secured to the head, a pair of hydraulic cylinders in the handle in open communication with each r.

upon suicient misalignment of the head, the

smaller piston is forced a predetermined distance out of the cylinder.

7. A yielding torque applying tool comprising a hollow handle, a work engaging head pivotally carried by the handle and normally aligning therewith but adapted to be swung to a position at an angle thereto, axially slidable abutment means within the handle against which said workengaging head may exert a camming action, said head and said means being in contact to transmit torque from the handle to the head, a spring setting up a resistance to the movement of said abutment means, a longitudinally movable reaction member engaging said spring, a piston within and movable longitudinally of the handle up* on camming movement of said head on the abutment means, a hollow housing rotatably mounted on the handle and having a threaded engagement with said reaction member, a battery in the hollow housing, an electric lamp carried by the housing and in open circuit electric connection with the battery and means within the hollow handle for completing the circuit from the lamp to the battery when torque applied to the handle has swung it to a predetermined angle with the head and has moved said piston longitudinally a predetermined amount.

8. A tool comprising a hollow handle, a pair of aligned communicating hydraulic cylinders within the handle, the cylinders having an incompressible fluid therein, a larger piston and a smaller piston axially slidable in the respective cylinders, a work-engaging head relatively movably carried by the handle and in contact with the larger piston to slide the larger piston into its cylinder upon relative movement of the head and handle, a spring resisting the expulsion of the smaller piston from its cylinder, a spring reaction member carried by the handle, a battery, an electric light, a normally open circuit for the light and battery, and means carried by the smaller piston for closing the circuit when, upon sufficient misalignment of the head, the smaller piston is forced a predetermined distance out of its cylinder.

ALLEN J. MELLERT.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 1,271,365 Reynolds July 2, 1918 1,519,800 Riiiiand Dec. 16, 1924 1,837,606 Barkis Dec. 22, 1931 1,837,645 Baash et al Dec. 22, 1931 1,860,871 Pouliot May 31, 1932 2,190,967 Zimmerman Feb. 20, 1940 2,244,185 Bakewell June 3, 1941 2,250,941 Zimmerman July 29, 1941 2,303,411 Van I-Iorn Dec. 1, 1942 2,398,392 Page Apr. 16, 1946 FOREIGN PATENTS Number Country Date 144,717 Great Britain Nov. 4, 1920 480,516 Great Britain Feb. 23, 1938 

